1. Field of the Invention
The invention relates to a motor vehicle having an internal combustion engine, a fuel tank and a tank ventilation device.
2. Description of the Related Art
U.S. Pat. Nos. 6,279,547 B1 and 6,067,967 disclose generic motor vehicles.
To meet ever more stringent environmental requirements, in modern motor vehicles, an activated carbon filter is installed in the region of a tank ventilation arrangement. The activated carbon filter is intended to prevent an undesired escape of hydrocarbons into the environment. Activated carbon filters conventionally serve merely as a buffer for hydrocarbons, and must be flushed while the internal combustion engine is running in view of their finite volume. Flushing is carried out, in a known way, by means of a negative pressure in an intake tract of the internal combustion engine. The greater the magnitude of the negative pressure, the more hydrocarbons can be sucked out of the activated carbon filter. In conventionally driven motor vehicles, flushing is sufficient to be able to always keep the filter action of the activated carbon filter at an adequately high absorption level. However, in hybrid vehicles, no flushing of the activated carbon filter takes place during electric driving. Thus, under some circumstances, a situation may arise in which the absorption capacity of the activated carbon filter is exceeded, and subsequently hydrocarbons could be discharged into the atmosphere. This situation must imperatively be avoided.
Therefore, the present invention is concerned with increasing storage capacity for hydrocarbons for a generic motor vehicle.